Saw chain



y 1967 G. L. ROBINSON 3,329,183

SAW CHAIN Original Filed July 13, 1964 I N VENTOR. 591:7 Z, film Inf BYm, AMVW United States Patent Ofi ice 3,329,183 Patented July 4, 19673,329,183 SAW CHAIN Gareth L. Robinson, Bridgenorth, Ontario, Canada,assignor to Outboard Marine Corporation, Waukegan,

111., a corporation of Delaware Continuation of application Ser. No.382,133, July 13, 1964. This application Aug. 8, 1966, Ser. No. 571,130

13 Claims. (Cl. 143--135) This application is a continuation ofapplication Ser. No. 382,133, filed July 13, 1964, now abandoned.

The invention relates generally to chain saws and more particularly tosaw chains used on such saws.

As is well known, during use a saw chain is normally guided in a grooveor track in the peripheral edge of a cutter bar and travels, at theouter end or nose of the cutter bar, about a path having a relativelysmall radius. Such saw chains commonly carry an articulated series ofcutting teeth which are located in raised relation to the chain properand which are spaced along the chain with gaps or voids present in thearea above the chain proper between successive cutting teeth.

This arrangement presents safety problems resulting from attemptedcutting action of the cutting teeth when traversing the rounded nose ofthe cutter bar and when the chain saw is employed in the cutting ofrelatively small diameter timber such as brush and branches.

In the first instance, during the initial part of the travel of acutting tooth around the relatively sharply curved cutter bar nose, thecutting edge has a tendency to attempt a thicker cut or slice of woodthan the cutting tooth is capable of removing. This situation occurseven with teeth having a so-called depth gauge located in forwardlylocated, relatively closely adjacent relation to the cutting edge. Suchattempted penetration of the cutting edge at an excessive depth duringinitial travel around the nose of the cutter bar causes kick-back orabrupt bodily movement of the chain saw upwards out of the cut towardthe operator.

When cutting timber of smaller diameter, the relatively deep and sharpvalleys or voids between successive teeth, or between the trailing partof one tooth and the depth gauge adjacent the next tooth, can result ingripping or snagging of the smaller diameter timber with consequentpossible injurious effects to the operator.

In accordance with the invention, the above two disadvantages areeliminated or at least substantially minimized by the use of a safetylink including a tang which extends outwardly beyond the chain properinto the previously existing void or cavity between adjacent teeth. Theouter edge of the tang is designed, when' cutting smaller timber, to atleast partially fill the voids between adjacent teeth, thereby tominimize any possibility of snagging or catching a limb or branch. Whentraveling around the nose of the cutter bar, the tang is displacedoutwardly relative to the cutter bar, either to prevent cuttingengagement of the wood by the following cutting tooth or to limit thethickness of the possible cut.

In the specifically disclosed construction, the safety tang is formedintegrally with a center link and extends rearwardly with respect to thedirection of chain advance into a position above the leading portion ofthe succeeding center link and into adjacent relation to the succeedingdepth gauge or cutting edge, as the case may be.

Other objects and advantages of the invention will become known byreference to the following description and the accompanying drawings inwhich:

FIGURE 1 is a side elevational view of a center link in accordance withthe invention;

FIGURE 2 is an end elevational view of the link shown in FIGURE 1;

FIGURE 3 is a fragmentary view of a cutter bar with a segment of sawchain guided thereon; :and

FIGURE 4 is a top elevational view of the saw chain segment shown inFIGURE 3.

Fragmentarily shown in FIGURE 3 is a cutter bar 11 having a rounded nose13 and a peripheral groove 15. The specifically disclosed saw chain 17includes a series of opposed pairs 2, 3, 4, 5, 6, and 7 of right andleft hand side links 21, 22, 31, 32, 41, 42, 51 and 52, each having alink portion with a forward or leading portion a and a trailing orrearward portion b and with an upper margin. Every other of said linkpairs 2, 3, 4, 5, 6 and 7 alternately includes either a left or righthand cutting link, which cutting links are generically indicated by 25'.Each of the cutting links 25 includes a cutting tooth or portion 26having along the forward or leading margin a cutting edge 27 whichextends, as seen best in FIG. 4, transversely of the chain for at leastone half of the width of the chain. The cutting links 25 can includedepth gauges 24, as shown, or can be constructed without depth gauges.

Located between successive pairs of spaced links are center links 28which are disposed between the links of each pair and which include amain portion or link part 29 including a forward or leading portion 30with a leading edge and a rearward or trailing portion 34 with atrailing edge. Each center link 28 also includes an upper margin 33 andcan include, as shown in the drawings, a driving tang 35 which dependsfrom the main part 29 and is adapted for receipt in the peripheralgroove 15 to guide chain travel and for engagement by a sprocket (notshown) to cause chain movement.

The various links are connected together in articulated relation bymeans in the form or rivets 37 or the like joining the leading portion30 of each center link 28 with the trailing portion 15 of each of thelinks in the forwardly adjacently located pair of opposed links and byrivets 37 or the like joining together the trailing portion 34 of eachcenter link 28 with the leading portion a of the rearwardly adjacentpair of opposed links. The construction thus far described is generallyconventional.

The advantages of the invention are obtained by providing various of thecenter links 28 with an upper or safety tang. As shown, the tangs 45project from the upper margin 33 of the trailing portion 34, each tang45 including an end poltion 47 and a. connecting portion 49.

The end portions 47 extend wholly above the upper margin 33, and in theconnected chain, extend above the leading portion 30 of the rearwardlyadjacent center link 28 to adjacent the depth gauge 24 carried by thenext cutting link 25. In the event that cutting links without depthgauges are employed, the end portion 47 can extend to adjacent thecutting tooth 26. The upper edge 53 of the end portion 47 of the safetytangs 47 is convexly curved to aiford smooth travel in the kerf at thenose 13 of the cutter bar 11. The lower edge 55 of the tang end portion47 is generally straight, being disposed in slightly spaced overlyingrelation to the upper margin 33 of the succeeding center link 28 whenthe chain is traveling along the elongated relatively flat edge of thecutter bar.

The connecting portion 49 includes a convexly curved upper edge 57 whichmerges smoothly with the upper edge 53 of the end portion and whichterminates at the upper margin 33 of the main part 29. The lower edge 59of the connecting portion 49 is concavely formed, merging smoothly withthe lower edge 55 of the end portion 47, and the trailing edge 63 of thecenter link trailing portion 34.

In operation, as the saw chain 17 travels around the nose 13 of thecutter 'bar 11, the resulting articulation of a") the saw chain servesto space the upper or outer edge 53-57 of the tang 45 at a greaterdistance from the periphery of the cutter bar 11 as compared to thecondition during travel along the relatively flat elongated part of thecutter bar. Consequently, engagement of the tang edge 53-57 with thekerf spaces the cutter bar 11 from the kerf at a sufiicient distance toeither eliminate kerf cutting at the nose 13 or to limit such cutting todepths which do not cause serious kick-back problems. The convexcondition of the tang edge 53-57 serves to provide smooth travel of thechain in the kerf during movement around the nose 13 of the cutter bar11.

When cutting relatively small diameter timber, the presence of the tang45 between the cutting links 25 serves to at least partially fill thepreviously existing voids, and thereby prevents snagging of such smalldiameter timber,

Various of the features of the invention are set forth in the followingclaims.

What is claimed is:

1. A link for a saw chain, said link comprising a main portion having alower margin, leading and trailing edges, an upper margin extending fromsaid leading edge, said upper margin including a flat edge merging withsaid leading edge, a lower tang extending from said lower margin, and anupper tang extending from said main portion between said trailing edgeand said fiat edge of said upper margin, said upper tang having an endportion located entirely above said supper margin of said main portionand a convex upper edge, said upper tang also having a connectingportion joining said end port-ion to said main portion, said connectingportion having a lower concave edge merging into the lower edge of saidend portion and said trailing edge of said main portion, and an upperconvex edge merging into said convex upper edge of said end portion andterminating at said upper margin of said main portion.

2. A saw chain comprising a first pair of opposing right and left sidelinks each having leading and trailing portions, only one of said firstpair of side links having a cutting edge, a first non-cutting centerlink having leading and trailing portions, means pivotally connectingsaid trailing portion of said first center link and said leadingportions of said first pair of side links, a second pair of opposedright and left side links each having leading and trailing portions,means pivotally connecting said leading portion of said first centerlink and said trailing portions of said second pair of side links, asecond non-cutting center link, said second center link having a mainpart with leading and trailing portions and an upper margin and a tangextending above said upper margin and rearwardly of said trailingportion of said main part toward said cutting edge into partiallyoverlying relation to said leading portion of said first center link,and means pivotally connecting said trailing portion of said secondcenter link and said leading portions of said second pair of side links.

3. A saw chain comprising a first pair of opposing right and left sidelinks each having leading and trailing portions, one of said first pairof side links having a cutting edge extending transversely for at leastone-half of the width of the chain, a first non-cutting center linkhaving leading and trailing portions, means pivotally connecting saidtrailing portion of said first center link and said leading portions ofsaid first pair of side links, a second pair of opposed right and leftside links each having leading and trailing portions, means pivotallyconnecting said leading portion of said first center link and saidtrailing portions of said second pair of side links, .a secondnon-cutting center link, said second center link having a main part withleading and trailing portions and an upper margin, and a tang extendingabove said upper margin and rearwardly of said trailing portion of saidmain part toward said cutting edge, in partially overlying relation tosaid leading portion of said first center link, and means pivotalllyconnecting said trailing portion of said second center link and saidleading portions of said second pair of side links.

4. A saw chain comprising a first pair of opposing right and left sidelinks each having leading and trailing portions, only one of said firstpair of side links having a cutting edge extending transversely of thechain, a first non-cutting center link having leading and trailingportions, means pivotally connecting said trailing portion of said firstcenter link and said leading portions of said first pair of side links,a second pair of opposed right and left side links each having leadingand trailing portions, means pivotally connecting said leading portionof said first center link and said trailing portions of said second pairof side links, a second non-cutting center link, said second center linkhaving a main part with leading and trailing portions and an uppermargin and a tang extending above said upper margin and rearwardly ofsaid trailing portion of said main part toward said cutting edge intopartially overlying relation to said leading portion of said firstcenter link, said tang including an end portion located entirely abovethe upper margin of said main part and rearwardly of the trailingportion of said main part, said end portion having a convex upper edge,said tang also having a connecting portion joining said end portion tosaid main part, said connecting portion having a lower concave edgemerging into the lower edge of said end portion and into the edge ofsaid trailing portion of said main part and an upper convex edge merginginto said upper convex edge of said end portion and terminating at saidupper margin of said main part, and means pivotally connecting saidtrailing portion of said second center link and said leading portions ofsaid second pair of side links.

5. A saw chain comprising a first pair of opposing right and left sidelinks each having leading and trailing portions, only one of said firstpair of side links having a cutting edge extending transversely for atleast one-half of the width of the chain, a first center link havingleading and trailing portions and being without a cutting edge, meanspivotally connecting said trailing portion of said first center link andsaid leading portions of said first pair of side links, a second pair ofopposedright and left side links each having leading and trailingportions, said second pair of side links being without cutting edges,means pivotally connecting said leading portion of said first centerlink and said trailing portions of said second pair of side links, asecond center link, said second center link being without a cutting edgeand having a main part with leading and trailing portions and an uppermargin, and a tang extending above said upper margin and rearwardly ofsaid trailing portion of said main part toward said cutting edge inpartially overlying relation to said leading portion of said firstcenter link, said tang including an end portion located entirely abovethe upper margin of said main part and rearwardly of the trailingportion of said main part, said end portion having a convex upper edge,said tang also having a connecting portion joining said end portion ofsaid main part, said connecting portion having a lower concave edgemerging into the lower edge of said end portion and into the edge ofsaid trailing portion of said main part and an upper convex edge merginginto said upper edge of said end portion and terminating at said uppermargin of said main part, and means pivotally connecting said trailingportion of said second center link and said leading portions of saidsecond pair of side links.

6. A saw chain comprising a first pair of opposing right and left sidelinks each having a link part with leading and trailing portions andwith an upper margin, one of said first pair of side links having atransversely extending cutting edge, a first non-cutting center linkhaving a link part with leading and trailing portions and an uppermargin, means pivotally connecting said trailing portion of said firstcenter link and said leading portions of said first pair of side links,a second pair of opposed right and left side links each having a linkpart with leading and trailing portions and with an upper margin, meanspivotally connecting said leading portion of said first center link andsaid trailing portions of said second pair of side links, a secondnon-cutting center link, said second center link having :a link partwith leading and trailing portions and an upper margin, and a tangextending above said upper margin and rearwardly of said trailingportion of said link part toward said cutting edge in partiallyoverlying relation to said upper margin of said leading portion of saidfirst center link, and means pivotally connecting said trailing portionof said second center link and said leading portions of said second pairof side links, said upper margins of said link parts being located inspaced relation from said cutting edge in a direction normal to theintended direction of chain travel.

7. A saw chain comprising a first pair of opposing right and left sidelinks each having a link part with leading and trailing portions andwith an upper margin, one of said first pair of side links having acutting edge extending transversely of the chain, a first non-cuttingcenter link having a link part with leading and trailing portions andwith an upper margin, means pivotally connecting said trailing portionof said first center link and said leading portions of said first pairof side links, a second pair of opposed right and left side links eachhaving a link part with leading and trailing portions and with an uppermargin, means pivotally connecting said leading portion of said firstcenter link and said trailing portions of said second pair of sidelinks, a second non-cutting center link having a link part with an uppermargin and leading and trailing portions, and a tang extending from saidupper margin, said tang having a pointed end portion located entirelyabove said upper margin of said link part of said second center link andrearwardly of said trailing portion of said link part of said secondcenter link and extending into overlying relation to said upper marginof said leading portion of said first center link, and means pivotallyconnecting said trailing portion of said second center link and saidleading portions of said second pair of side links.

8. A link for a saw chain, said link comprising a link part havingleading and trailing edges, an upper margin extending from said leadingedge, said upper margin including a flat edge merging with said leadingedge and a single tang extending from said link par-t between saidtrailing edge and said flat edge of said upper margin, said tang havinga single pointed end located above said upper margin and rearwardly ofsaid trailing edge, said pointed end pointing rearwardly, said uppermargin adjacent said leading edge being spaced below said pointed end ofsaid tang.

9. A link for a saw chain, said link comprising a link part havingleading and trailing edges, an upper margin extending from said leadingedge and having a flat edge part, and a single tang extending from saidlink part between said trailing edge and said fiat edge part of saidupper margain, said tang having a single pointed end portion locatedabove said upper margin and rearwardly of said trailing edge, said endportion having a convex upper edge extending from said flat edge part tothe end of said end portion, said upper margin adjacent said leadingedge being spaced below said pointed end portion of said tang.

10. A link for a saw chain, said link comprising a link part having anarcuate leading edge, an upper margin extending from said leading edge,said upper margin having a fiat edge merging with said leading edge, atrailing edge, and a tang extending from said link part between saidtrailing edge and said flat edge of said upper margin, said tang havinga pointed end portion located above said fiat edge and rearwardly ofsaid trailing edge, said end portion having a convex upper edge and alower edge, said tang also having a connecting portion joining said endportion to said link part, said connecting portion having an upperconvex edge merging into said convex upper edge of said end portion andterminating at said upper margin adjacent said flat edge.

11. A saw chain comprising a plurality of side cutting links alternatelylocated along the length of the chain, a plurality of non-cutting linksconnected with said cutting links to form said chain, one of saidnon-cutting links having a tang occupying at least a portion of thespace between adjacent cutting links and extending beyond one end ofsaid one non-cutting link into partially overlying relation to theadjacent end portion of an adjacent noncutting link.

12. A saw chain comprising a plurality of longitudinally spaced centerlinks, a plurality of longitudinally spaced pairs of right and left sidelinks in the spacings between said center links, each of said centerlinks and said side links having a main part with an upper margin andleading and trailing end portions, means serially and pivot-allyconnecting said center links to said pairs of side links, some of saidside links having thereon cutting edges and the remainder of said sidelinks and said center links being non-cutting links, said cutting edgesbeing located only on one of said side links of any one of said pairs ofside links and said cutting links being alternately located on oppositesides of said saw chain, and some of said noncutting links having tangsextending above said upper margins and beyond one of said end portionsinto partially overlying relation to adjacent end portions of adjacentlylocated non-cutting links.

13. A saw chain comprising a plurality of links each having a main partwith an upper margin and leading and trailing portions and including afirst pair of opposing right and left side links, said right side linkof said first pair of side links having a cutting edge and said leftside link of said first pair of said links being a non-cutting link, afirst non-cutting center link, a second pair of opposed right and leftside links, said second pair of side links being non-cutting links, asecond non-cutting center link, and a third pair of opposed right andleft side links, said left side link of said third pair of side linkshaving a cutting edge and said right side link of said third pair ofside links being a non-cutting link, means pivotally connecting saidtrailing portion of said first center link and said leading portions ofsaid first pair of side links, means pivotally connecting said leadingportion of said first center link and said trailing portions of saidsecond pair of center links, means pivotally connecting the trailingportion of said second center link and said leading portions of saidsecond pair of side links, and means pivotally connecting said leadingportion of said second center link and said trailing portions of saidthird pair of side links, one of said non-cutting links having a tangextending above said upper margin, lengthwise of said chain beyond oneof said leading and trailing portions of said one noncutting link, andinto partially overlying relation to the adjacent portion of an adjacentnon-cutting link.

References Cited UNITED STATES PATENTS 2,725,083 11/1955 Ackley 143-4 353,176,733 4/1965 Dobbertin 143--135 DONALD R. SCHRAN, Primary Examiner.

1. A LINK FOR A SAW CHAIN, SAID LINK COMPRISING A MAIN PORTION HAVING ALOWER MARGIN, LEADING AND TRAILING EDGES, AN UPPER MARGIN EXTENDING FROMSAID LEADING EDGE, SAID UPPER MARGIN INCLUDING A FLAT EDGE MERGING WITHSAID LEADING EDGE, A LOWER TANG EXTENDING FROM SAID LOWER MARGIN, AND ANUPPER TANG EXTENDING FROM SAID MAIN PORTION BETWEEN SAID TRAILING EDGEAND SAID FLAT EDGE OF SAID UPPER MARGIN, SAID UPPER TANG HAVING AN ENDPORTION LOCATED ENTIRELY ABOVE SAID UPPER MARGIN OF SAID MAIN PORTIONAND A CONVEX UPPER EDGE, SAID UPPER TANG ALSO HAVING A CONNECTINGPORTION JOINING SAID END PORTION TO SAID MAIN PORTION, SAID CONNECTINGPORTION HAVING A LOWER CONCAVE EDGE MERGING INTO THE LOWER EDGE OF SAIDEND PORTION AND SAID TRAILING EDGE OF SAID MAIN PORTION, AND AN UPPERCONVEX EDGE MERGING INTO SAID CONVEX UPPER EDGE OF SAID END PORTION ANDTERMINATING AT SAID UPPER MARGIN OF SAID MAIN PORTION.